A method for reducing stress in animals, such as pigs in an overcrowded breeder, by exposing a block to be licked by the animals. The block contains at least 50% by weight and preferably at least 70% by weight glucose, has a compressive strength over 5 kg/cm.sup.2 preferably 50-150 kg/cm.sup.2, and a water contentof 0.1-20% by weight. The block is too large to be swallowed by the animals and its compressive strength prevents crumbling. It is at least 50 g in weight, e.g. 500 g, and each dimension is more than 2 cm. The block is preferably secured above ground level and is slowly consumed by the animals by licking or pecking.

Claim:

What is claimed is:

1. A method of enhancing the growth of domestic animals and improving the feed conversion ratio of feed provided to said domestic animals wherein said domestic animals areselected from the group consisting of cattle and poultry, comprising causing said domestic animals, whereby growth of said domestic animals and the feed conversion ratio of feed provided to said domestic animals are both enhanced to consume as asupplemental foodstuff by licking, a sugar block consisting essentially of glucose and having a hardness such that said block does not easily crumble, said block having a compressive strength in the range of 50 to 150 kg/cm.sup.2 and a water content of0.2 to 15% by weight, said block having a weight of at least 500 g, each dimension of said block being greater than 2 cm, and said block being suspended at a height above ground level accessible to licking by said animals, said block being formed in theshape of a doughnut having a hole of a size sufficient to accommodate the nose of one of said animals.

Description:

BACKGROUND OF THE INVENTION

This invention relates to a method for reducing stress in animals, and a block for use in practicing the method. The invention is particularly useful for the reduction of tail biting and ear biting among pigs caused by stress in an overcrowdedbreeder during the fattening stage and the wearing period. The invention is further useful for reducing the incidence of cannibalism among poultry, and improving the feed conversion ratio and weight gain of cattle and swine.

Growth promotion of animals by feeding them powder, granules or pellets with added vitamins, minerals or fatty oils and molasses is known. (Jap. Pat. Unexam. Publ. No. 56-144059 and No. 58-47442.) Furthermore, in order to balance sodium forherbivora which are fed high potassium content grass, highly compressed sodium chloride blocks can be licked (Jap. Pat. Unexam. Publ. No. 55-26814). These prior known breeding methods are not for relieving stress in animals.

Stress syndromes of animals are caused by three primary factors, namely nutrients, circumstances and psychological factors, for example lack of a sufficient number of feeding vessels, insufficient water supply, noise, sudden change of bedtemperature in animal barns, insufficient ventilation, high humidity of beds, overcrowded breeding and lack of exercise. Among these, overcrowded breeding is a serious problem. For example, in the case of overcrowded breeding of pigs, discomfortsyndromes such as tail biting and ear biting occur. (Disease of pig: Kindai Publ. Co., p. 745, 1983) In order to prevent these stresses and for avoiding dullness in pigs, iron chains or used tires are hung for the pigs to bit, or straw bedding issupplied in the pigsty for biting. An increase in the number of stress syndromes in pigs can coincide with a period of introducing new breeding administratiOn systems and modern breeding methods, for example an expansion of the breeding scale, andautomated centralized administration of the pigsty and the labor system are thought to affect the attitude and temper of pigs and may cause undesirable results. In the case of poultry, these conditions promote increased cannibalism (e.g. tail-pecking),and this cannibalism is a leading cause of death among poultry subject to these conditions. In the case of swine, cattle and poultry, these conditions decrease the animals' weight gain and increase the feed conversion ratio (feed intake/weight gain).

OBJECTS OF THE INVENTION

Accordingly, it is an object of the present invention to provide a method for preventing stress syndromes in animals.

Another object of the present invention is to provide a method of breeding for animals by supplying a feed substance that also prevents stress syndromes in animals, for example tail biting and ear biting among swine and cannibalism among poultry.

A further object of the present invention is to provide a breeding method characterized by improved growth promotion and higher feed conversion ratio.

Still another object of the present invention is to provide an edible material for achieving the above objects.

SUMMARY OF THE INVENTION

We have found that stress can effectively be avoided by making a pig, calf, or hen bite or lick a glucose block of a size and hardness such that it is not easily swallowed. Furthermore, we have found that the feed conversion ratio can beimproved by stimulating salivation and the ingestive nerve centers. Moreover, essential components such as vitamins, minerals and feed components for animals, for example electrolytes for preventing dehydration in calves and physiological irondeficiency in piglets, can advantageously be added as ingredients of the sugar block.

A sugar block according to the present invention comprises glucose as its main component and has a shape and hardness which are not easily swallowed by animals and not easily crumbled.

Molding of the sugar block can be effected, for example, in the following three ways;

1. Glucose powder is press-molded. Stearic acid or magnesium stearate can preferably be added as a lubricant.

2. Glucose solution is allowed to solidify in a suitable vessel.

3. A previously molded solid glucose block is cut to suitable shape.

The reasons why glucose (over 50% w/w) is selected as the main component are that polysaccharides such as starch, dextrin, lactose or sucrose cannot directly be absorbed but are absorbed after digestion in vivo, are easily covered with mold(fungi) or are less sweet. Also sucrose has the disadvantage of abnormal fermentation in the intestine; while fructose and xylose are expensive.

The size, shape and hardness of the sugar block are preferably as follows:

(1) Weight: Over 50 g, preferably over 500 g, even over 25 kg according to the kind of animal. The amount in the case of piglets is preferably the amount piglets (approximately 10 piglets) can eat within 1-3 weeks.

(2) Shape: Length and width: over 2 cm. Spherical, cylindrical stick, rectangular stick, truncated cone, hemisphere, hollow shape such as doughnut and bowl-shaped. Hanging type is preferable to maintain sanitary conditions by avoiding touchingthe ground. Doughnut or stick type of sugar block is preferable. In case of doughnut type, its inner diameter should have a size which the animal's nose or beak can easily enter. A small diameter can be used for young animals and a larger diameter forgrown animals. For licking the sugar block, a cylindrical stick rectangular prism or other shape is preferably selected. A protector such as plastic can be attached to the sugar block for controlling crumbling.

Starch enzymatic hydrolyzate glucose solution was concentrated in vacuo to prepare a Brix (20.degree. C.) 85 glucose solution. Purified glucose powder was added at 3% w/w thereto. The mixture was poured into a cylindrical vessel, diameter 4cm, length 30 cm, and allowed to stand one day and one night at room temperature to harden, then the vessel was removed.

Sugar block, cylindrical, weight 500 g was obtained.

Water content: 10.5%. Compressive strength: 90 kg/cm.sup.2.

Brix-value, water content and compressive strength obtained by the said crystallization procedure are shown in Table 1.

Dextrin 5% and magnesium stearate 1% were mixed with purified glucose powder, and introduced into a mortar vessel, 27.5 cm long, 7 cm wide. The mixture was pressed with a hydraulic press to prepare various shapes to sugar blocks. In Table 2,the relationship of the width of the block and compressive strength, tested on piglets, is set forth. The water content was 9.5%.

Piglets, 6.5 kg weight at the weaning period, were bred for 4 weeks and observed as to body weight increase and effective feed conversion ratio.

A sugar block supplied group and a sugar block unsupplied group (control) were set up. The tested groups and the observations are shown in Table 3. The tests were performed three times. Commercially available feed was used during each testperiod. Water was freely supplied. The results are shown in Table 4. The body weight increase measured twice in the test period 0-2 weeks and 2-4 weeks, and three times in the test period-4 weeks (the entire period) are shown to be significantlydifferent from the controls at P<0.05. Improvement in the effective feed conversion ratio was observed. In the control group, much struggling of the individuals was observed and many incompletely grown piglets were found. In the sugar blocksupplied group, no or less struggling was observed and each individual grew steadily.

TABLE 3 ______________________________________ Frequency of Observation No. of Amount Sugar of Feed General Test No. of Blocks Body Con- Obser- Group Animals Supplied Weight sumption vation ______________________________________ Sugar 10One block Week 0 Week 2 Observed block at any time, (starting) and 4 (at every day supply replaced test). the end when con- Week 2, of test) sumed. week 4 (at the end of test) Control 10 -- Same as Same as Same as above above above ______________________________________ Note: All tests were performed three times.

Effectiveness of prevention of stress in pigs

Piglets, 30 kg in weight, in the sugar block supplied group (15 piglets) and sugar block unsupplied group (control, 15 piglets), were bred under overcrowded breeding conditions in a 5 m.sup.2 area. General symptoms were observed for two weeks. In the control group, on the 7th day after the start of the test, many struggling piglets were observed, and on the 9th day many piglets bleeding from the tail and ears, from bites, were found.

On the contrary, in the sugar block supplied group, less struggling was observed, and no tail bites were found during the test period (refer to Table 5).

It will therefore be seen that supplying sugar blocks of the present invention produces a relaxation of stress in pigs.

Further test for improvement in body weight increase and effective feed conversion ratio in pigs:

Study period, May 29, 1985-Jul. 1, 1985 (33 days).

32 weaned piglets produced by four sows and having an average age of 31 days, were used. The animals were divided into two groups of 16 piglets each, a test group provided with the sugar block according to the present invention, and a controlgroup. The test group was supplied with two sugar blocks suspended in the pen throughout the observation period. Both groups were fed prestarter feed for piglets from the start of the experiment until day 12, and starter feed thereafter until day 33. Body weight was measured on days 0, 12 and 33. Weight gain and cumulative feed intake were measured on days 12 and 33. Clinical observations were taken daily.

The test group showed increased weight gain and decreased feed conversion ratio, during both periods of day 0-12 and day 12-33, as compared with the control group (see Table 6). Feed intake increased in the test group, the subjects of which hada lower incidence of diarrhea and fought less than those of the control group. Most animals in the test group had improved coat glossiness and florid skin.

There were used eight male Holstein calves having an average weight of 55 kg each. The animals were divided into two groups of four calves each, a test group provided with the sugar block according to the present invention, and a control group. Each member of the test group had a said sugar block fixed to its feeding trough throughout the study period. Both groups were fed a diet of milk substitute and milk replacer in pellet form during the 45 days of the experiment.

These results show that the test group displayed increased weight gain and feed intake, and decreased feed conversion ratio (feed intake/weight gain), relative to the control group.

Test for prevention of cannibalism in poultry:

Study period, Mar. 17, 1986-Apr. 25, 1986 (40 days).

There were used 1000 Shaver Star Cross hens having an average age of 16 weeks. The animals were divided into two groups of 500 hens each, a test group provided with the sugar block of the present invention, and a control group. The hens of eachgroup were placed in 50 cages, ten hens per cage. A sugar block according to the present invention and measuring 7.times.7.times.3 cm, was suspended in the center of each of the 50 cages of the test group. Each day of the study period, the number ofincidents of cannibalism was recorded.

The results of this test are shown in Table 8:

TABLE 8 ______________________________________ Test Group Control Group ______________________________________ Incidents of cannibalism 55 565 (total number, usually in the form of tail pecking) Number of deaths 8 32 ______________________________________

The test group show fewer incidents of cannibalism, and fewer deaths, due primarily to the decreased cannibalism.